Biohackers put magnets in their fingertips frequently. It's in the same vein as putting an NFC chip in your hand.

A real doctor won't do it, since it's body modification... it doesn't even classify as cosmetic surgery, so you have to go to like a tattoo/piercing place (or something sketchier) to get one outside of a scientific study. I think it falls under "do no harm" more or less, which is also why doctors won't do things like piercings despite being very qualified to do it safely and preventing infection in the process.

The hardest part is finding something to implant, since the body will readily reject a hunk of neodymium or iron in the body; so you need something that's either "biocompatible" or coated in a biocompatible substance, then sterilized. Finding a mostly sterile field and tools, then a quick incision and a few stitches later, and you have it installed.

Usually it's a neodymium magnet (to provide the highest magnetic field per gram), coated in a biocompatible film... there's a couple different biocompatible substances that can be used, the key is to get something that is durable, since your fingers get a lot of use, and something that will last a good long time so you don't have to get it removed and a new one sourced and implanted every few years.

No, I don't have one myself, but I've been interested in the neighboring implant, which is the NFC/RFID chip, and the idea is largely the same.

Do your research on it if you're considering it, it's incredibly easy to get the wrong magnet implanted, or something with a poor biocompatiblity layer on it (maybe it's too thin? Or poorly applied or something), so spend a bit more for a good product, and find a good place to get it implanted otherwise the infection may be quite the bitch to get over, and may require removing the implant before the infection clears up entirely.

Buyer beware on this one. 0/10 medical professionals recommend doing this.