There are basically two purely EM mechanisms at work for large static fields. First, if the field is big enough, it will saturate components that rely on EM ef

There are basically two purely EM mechanisms at work for large static fields. First, if the field is big enough, it will saturate components that rely on EM effect to work - these will stop functioning until they are removed from the field. Permanent damage possible if other components behave badly in this situation. The other thing is if you move in the field you will induce currents on anything like a conductive loop in your device. Damage potential is really dependent on the strength, speed of motion, and how sensitive your device is. Of course, if you have magnetic materials, mechanical damage is also possible. I suspect those fishing magnets fall off fast enough you'd have to get it lined up just right to a control board to see any effect, if then.