I removed the passcode from my iPhone before repair, has my data been compromized? Few days back I gave my iPhone 6 to a shop to change the battery. The person asked me to remove the passcode so that he can check the battery status. I collected the iPhone later when the battery was fixed. 

But now I think it was not a smart thing to do to remove my passcode and give the phone to someone else. I am now worried that he might possibly taken the backup of my iPhone to his iTunes and then restore it into a another iPhone. Will he get all my data in another iPhone?

Is there anything I can do now to prevent this?
You should consider all device content compromised and it is too late to be prevented.

By removing the passcode, any new computer the device is connected to can be ‘trusted’ without any further authentication. The device can be backed up to iTunes and all the device content available to browse through or be restored to a new device.

If the backup was created ‘encrypted’ this includes all passwords on the device which may include your Apple ID password.

You should change any passwords which are linked to the device, such as Apple ID and email account passwords.