Does a pickup microphone work in space (vacuum)?

A contact microphone is basically an accelerometer. It does not require any air for its operation.

if it is mounted on the same surface with the same vibrations, it in theory should measure nothing.

When sound waves propagate through solid material, it's not just the whole rigid object shaking back and forth: It's waves of strain.

Those strain waves will pass through a contact microphone that is attached to some small area of the surface. It will work better still if it can be wedged in between two different parts of some flexible structure:

^{Piezo pickup wedged into the bridge of a string bass (double bass)}