Phone hacking

as it stands unless your device is jailbroken the tools someone needs to hack it don't exist, outside of government pulling information out of service providers and satellites.

if you device is behaving erratically it can be traced back to a weak wi-fi and/or cellular signal.

In some instances it can save time backing up the device then restoring it to a factory condition. You will need to know your passcode before you do this, or you may run into problems later when the device is restored.

https://support.apple.com/en-us/HT201252

What makes you think they are?

The orange light coming on when you make phone calls is normal, it means you are using the microphone while you are talking to someone. What kind of noises? Most likely you are hearing notifications.