Security Concern

Hello, so I have reason to believe that the security of my phone has been compromised. I realize that iOS is a very hard to break into system and that the chances of this may be thankfully low. The reason I am posting here is because I have also talked to people who work in the IT security field that have talked about how it is part of their job to hack into systems. This includes iOS. I also realize that it would probably take considerable effort to do such a thing and for someone to install spyware onto my phone would be a pretty big waste of time for most. Still, I am concerned and wanted to know if anyone has suggestions to track data being sent from my phone or ways to reveal such an app or code. I do not know much about this sort of thing only what I have learned from light research through google. I have tried the commonly suggested solutions so wanted to get more input from people who are more knowledge and have experience.

Thank you