how to catch a smart man cheating!?

Pertaining  to a guy who keeps a lock on his phone, keeps it on him 24/7 everywhere he goes bathroom store etc... shares his location but then turns it off so it says location unavailable... all of us females know when we think something's up with our man, usually we're right... so just wanted to hear some of you smart ladies who figured it out to tell me if you were bugging or if you found out somehow..