Barry M..... may sound
...but you need to ask a few questions
1. is it only one jaw of your vernier calliper that attracts metallic swarf? ...remember a magnetic field is polarized with a north & a south pole
2. or is it the field set up between both jaws that attracts the swarf?
3. degaussing
is the term for removing permanent magnetism...[ships, aircraft, electronic components .........the list is endless]
4. magnetism created & generated in metals is usually by friction ....it is difficult to understand how this would occur in a pair of vernier callipers
5. one thing is that the function of the linear transducer in the calipers will not be affected by the magnetic field
I would do nothing apart from keeping them away from swarf............& continue to use them..........Derek