If someone did hack your phone you may never find out like most people. The average user does not have the proper tools or knowledge to trace the hack. You would need to go to local law enforcement and that may be a futile task anyways. With this becoming a more common issue, law enforcement does not have the resources to handle every case that occurs. Unless you are getting threats they wont consider this a top priority. Check with them to see how you should proceed. Make sure you reset ALL passwords from a clean device like a PC to prevent further breaches of your phone. What symptoms are you having that make you think you have been hacked?