Modern airport scanners that you put your hands up and the thing whizzes around you are not metal detectors. They don’t even penetrate the skin. They just use millimeter wave radar to look through your clothes to be able to see if you’re carrying any weapons.
As far as actual metal detectors go, a magnet can easily be found by one… But the large type you walk through would have to have its sensitivity turned up so high… probably to the maximum in order to detect such a small amount of metal inside the large area that constitutes the “doorway” you walk through. Handheld metal detector scanners and wands are sometimes pretty good at finding those kind of things… But I’ve never heard of many issues with people at airports simply because actual metal detectors aren’t used anymore with any kind of regularity.