App for protecting device from hacking

Are you talking about data you are receiving and transmitting being monitored or intercepted? Or are you talking about actually something being installed and used on the device? In the case of the former, you can use a VPN or PIA type of solution. In the case of the latter, there isn't really anything known in the wild that would just randomly on its own install and run on your device simply as far as you just accessing the internet (without installing any profiles on your devices or accepting any certificates or something like that).