First nice looking compass for Android Wear (for example Moto 360).
It also works on your Android Smartphone as well. The app shows you
the direction to magnetic north and also the strength of the magnetic field
in your area.

Instructions, requirements:

Instructions for "Wear Compass Pro" on your Android Wear (e.g. Moto 360):
* Smartphone has to be compatible with Android Wear. (at least Android 4.3.1)
* Android Wear has to be paired with your Smartphone. (Bluetooth + Android Wear App)
* After installing that app on your phone "Wear Compass Pro" will be automatically
installed on your Android Wear as well
* Your smartwatch will point to magnetic north (Accuracy depends on many factors)
* Simple calibration -> just move your device around on all three axis.

Instructions for "Wear Compass Pro" on your smartphone:
* Smartphone has to be at least Android Version 4.0.3
* Simple calibration -> just move your device around on all three axis.
* Your smartphone will point to magnetic north (Accuracy depends on many factors)

Requirements:
Please note that this app works with the integrated magnetic field sensors.
Due to that fact the accuracy of the compass is very sensitive and reacts
on environmental influences. So your result be distorted because of that.
If your devices does not have a magnetic field and orientation sensor it wont
be compatible.