how can i see who what and when other devices have had access to my phone

Check your device list to see if there is a device signed in that you don't recognize. You can remove the device using the steps in the article below. As a precaution, change your password.

Apple ID device list -Check to see where you‘re signed in.   * 

See who has access to your device or accounts

 Apple ID Password Change.   -  

ASC YouTube for How to reset your Apple ID password

 What to do after you change your Apple ID or password - Apple Support  -   I suggest doing this before you change your Apple ID or password.

No other devices have access to your phone. There is limited sharing if you print, use AirDrop, or use handoff with your Mac but nothing else