For polar alignment you don't need a compass at all.
When there is iron and steel in the neighborhood (telescope tube, mount parts) a compass will get inaccurate.
Just use the celestial south pole or the drift method.
I found out myself an alignment method with a bubble level and a wedge with an angle equal to your latitude. No compass, visible north or south pole needed.
http://sky.velp.info/eqmount.php
Or otherwise google for 'polar alignment telescope'.