The following are steps to follow in order to discover the app which might bug you. These below steps will also help you to find any application installed on your device is a bugging app or not.
1.Download the permission checker application from the play store.
3.Later open the permission checker app and check what kind of permissions is the app requiring. In the app you will also get a brief 1-2 line description for the type of permission used by the application.
If you see any irrelevant permission to the app or you find it suspicious then you can un-install it.
last but not the least if you still do not understand the description given by the permission checker app then you can google the permission in your local language which shall give you the complete description.
You can not completely avoid the privacy of your app as it also depends on the type of internet connection you are connected and the level of security it has(i.e. the WPA2-psk is the most preferred connection in terms of wireless but WEP will still do the bit),if the device itself is bugged then your are possibly being eaves dropped.