however I feel this offer isn't real.

https://searx.be/search?q=digital+magnetic+field+probe

(is anyone able to rescue yacy.net?  their public portal isn't functioning for me)

I intended to provide a real offer, but have not checked my funds and don't know where you live or if you are able to share a shipping address.

Update from my insanity: ferromagnetic particles don't emit a magnetic field.  I guess you would want a force sensor on the magnet, rather than a field probe.  (Sad.  I like field probes.)

If you offer stronger evidence smarter people than me will listen.

I bet searx has force measurement devices too though.