Using Late 2015 13" MacBook Pro as a 2nd monitor for Late 2015 27" iMac I have a Late 2015 13" MacBook Pro (HDMI, Thunderbolt 2, and USB 3) that I want to use as a 2nd monitor for my Late 2015 iMac (Thunderbolt 3 aka USB-C and USB 3).

What is the cheapest/best cable choices to hook them up? Is there way to use the Sidecar and Airplay software to set up this?
Using Late 2015 13“ MacBook Pro as a 2nd monitor for Late 2015 27” iMac


You cannot use a MacBook as an external display for an iMac.


  Is there way to use the Sidecar and Airplay software to set up this?


No.