Funny thing, but I always associate
Mica with a girl and pronounce it mee-kah and
Micah with a boy and pronounce it my-kah. I'm sure the name has a variety of pronunciations, but I never realized until I saw your post that I differentiate between the two.
I like it for a boy or a girl, but I feel like for a boy it needs the 'h' on the end to look a bit more masculine. It'd also make a cute nn, maybe for
Michaela? (Not sure if that name is to your taste).