Technically yes.
But I am unaware of any attempt to do this with airliners.
But there were several designs in the past which used a big airplane or a Zeppelin as a mother ship, which took fighters with it for air defense.
The B-36 was involved in several such designs.
In all cases the docking was made from below, because this gave the fighter pilot the best field of view and reduced the risk of a tail strike.
While the fighter in the picture above is a Republic F-84, McDonnell even designed one specifically for the purpose of being carried around by a bomber, the XF-85 Goblin .
It used a rather complicated trapeze for docking and was then pulled up into the fuselage, as the picture with a B-29 below shows.
Your design proposal with the simple platform on top of the fuselage would carry a high risk of a tail strike if anything goes wrong, so it is unlikely that this will ever be tried for real.
But when you change the airliner to a AN-225, the idea looks not totally impossible.
The Russians tried to dock a fighter with a mothership as early as the 1930s.
The picture below shows a TB-3 docking with a I-Z fighter, the first pair of aircraft in history to dock in flight.
The main reason for docking was the much smaller range of fighters.
Today, air refuelling takes care of this deficit, so it is unlikely that anyone will see a benefit strong enough to justify the expense of modifying two aircraft and the risk incurred in the docking process.
aviation.stackexchange.com/users/1961/Peter Kämpf
Parasite jet aircraft have been experimented with, the only purpose built one I know of is the XF-85 Goblin , there was also a modified F-84 Thunderjet which was used as well.
These experiments were abandoned because the process of launching and recovery was too hazardous, and air to air refueling made much more sense to extend the range of fighters.
It is possible to join 2 aircraft in the manner you describe, however it's extremely dangerous due to the aerodynamic forces involved, and there are no benefits which would make the risks worthwhile.
aviation.stackexchange.com/users/1791/GdD
It is not possible to replicate this process safely.
The pilot in the smaller aircraft can not see its gear and would have no idea where to "land".
And perhaps even more importantly, there's no out if the fighter has an emergency.
If the fighter loses control just above the carrier then its likely that both aircrews will die.
As has been pointed out in other posts, aircraft have been recovered underneath carrier airplanes in the past, and while dangerous, this leaves an obvious escape route in the event of an emergency.
aviation.stackexchange.com/users/4215/Rhino Driver
DARPA just happens to be asking for proposals on how to accomplish this very task: DARPA invites input on how to enable existing large aircraft to carry, launch and recover multiple unmanned air systems for a variety of missions
aviation.stackexchange.com/users/4359/dgig
As an addition to the projects described by Peter Kämpf, there was the Tip Tow project during the fifties where two fighters were attached to the wingtips of a B-29.
The idea was that the additional wingspan would increase the range of the bomber, while at the same time enable it to carry its own fighter escort which could attach and detach in the air as required.
While attached the fighters could switch off their engines, thus saving fuel for later.
While attached, the B-29 would control the flight surfaces of the attached F-84 (more specifically EF-84D) so that the pilot wouldn't have to do this manually, but during the first flight with this system enabled one of the fighters rolled on top of the B-29s wing, and the two aircraft crashed with no survivors.
The second F-84 survived as it was disconnected from the B-29.
aviation.stackexchange.com/users/13485/bjelleklang
Imagine this scenario:  A modified military 747 is flying at a constant speed and altitude. On the top of the fuselage there is a device like a helipad but with three holes to accommodate the fighter jet landing gear, when pressure is applied the holes close, locking the landing gear in the holes. The fighter is flying at the same speed and slightly above. With proper training, is it possible for the pilot to land on the plane and then shut off the engines?
Can a fighter jet land on a modified airliner?
aviation.stackexchange.com
<airliner><landing><flight-training><fighter><jet>
aviation.stackexchange.com/questions/9854
aviation.stackexchange.com/users/3493/user60684
It is possible for a jet fighter to land on an airliner but it is extremely dangerous. DARPA, however, is looking for proposals to perform exactly this task. There are examples of this being attempted in the past. In the 1930s, the Russians attempted to dock a fighter with a mothership. Experiments have also been conducted with parasite jet aircraft. However, although this process is technically possible, it would not be safe and the risks far outweigh the benefits. Interestingly, DARPA is currently requesting proposals for ways in which this action could be achieved.
Although this process is technically possible, it would not be safe and the risks far outweigh the benefits. There are examples where this has been attempted. In the 1930s, the Russians attempted to dock a fighter with a mothership. Experiments have also been conducted with parasite jet aircraft. DARPA is currently requesting proposals for ways in which this action could be achieved.