I have magnets implanted into two of my fingertips, which extend my sense of touch to be able to feel electromagnetic fields. I did an AMA on reddit a while ago that answers most of the common questions, but I'd be happy to answer any others.

To touch on it briefly, alternating fields feel like buzzing, and static fields feel like bumps or divots in space. It's definitely become a seamless part of my sensory experience, although most of the time I can't tell it's there because ambient fields are pretty weak.