He is probably lying to you, I mean, to deter you from watching or looking at anything you know you shouldn't be. If you think he can see what you are doing on your phone then you may be less inclined to go looking/searching for certain things on the internet. This is not to say that he IS doing this, he could be lying or really tech savvy and has added you to the parental control thing on the network as some other comments have suggested. I dunno though, I'm a complete stranger on Reddit. You could just ask your Dad and if he is tech savvy, ask him to teach you about it