I have a little button compass as a part of my ITS Urban SERE kit, and there is a magnometer built into my phone, for times when my GPS wont give me a location and bearing. However, compass navigation is something that is really important for everyone, and it pays to have backups as well as a primary.
This is the Silva Luminous Wrist Compass. It is a button sized luminous compass that is designed to fit directly on your watchband. This compass has 8 graduations for the cardinal and cross-quarter points (800 mils). North is marked out with a good solid red triangle. The other cardinal points are clearly marked, in orientation so that they are readable forwards regardless what your bearing is.
The compass fits directly onto your watch band with the built in flattened loop band, but only if your watch band is narrow enough. The band I put onto my Pebble is too wide, and though a baracord bracelet would be a perfect place to add it.
With its luminous face, the compass is visible in dark environments with only a brief exposure to light, say the residual charge from a days outdoor activity.
I have attached mine to the ITW Grimloc carabiner I have on my Hazard4 Loader RG holster harness.
In prime position for me to glance down and take a bearing.
Being a little compass, it is not super accurate, given that it only has eight points, and had a bit of variance when I compared it to my other compasses, but as an EDC, holdout compass, it is all but weightless and takes up no space.