How can I ensure that my father isn’t spying on me via my iPhone?

Hi everyone, I am an 18 year old male who is going off to college soon. Despite me paying my share of the phone bill, I have a very controlling father who likes to spy on his children via apps such as Find My iPhone. I know this because I’ve seen him spy on my 23 year old sister from time to time (who lives independently and also deserves her privacy).

Before I go off to college I was wondering …

father iphone isn privacy spying