If your compass has adjustable declination, alter it to the number of degrees for your location. This may be a moving bezel ...

My wife and I enjoy hiking off trail and for our bushwhacking adventures, we use a paper topographic map, a compass and a handheld GPSR.

Once the compass has been calibrated, the compass at 0 degrees will point to magnetic north - this differs from True North. If you want your iPhone's compass to always point to True North ...