First off what makes you think that? Has anyone else had control of your IPhone? Only thing that comes to mind right off is someone could turn on the share my location on your phone then they could tell where you are whenever they want to?
If you're jail broken, check your installed packages in Cydia. Most spyware can be installed from there. But again, spying software use "normal" names. So you have to know what you're looking for.
You can also try checking if you have any unknown profiles installed on your device. Especially ones you know you didn't install.
Settings - general - profiles