[AC Question]

Will this magnetic ball cell holder damage my galaxy s6

[Mike Dee]

Welcome to Android Central.
To answer your question:
Probably not if you are worried about the magnet, but it would be helpful if you posted a link to the product and what your actual concern is?

[Rukbat]

If you're talking about something like the Seelie mount, no. There's no magnetic component in the phone. I suspect, though (I don't own one, but I'm thinking of ordering one), that the compass in the phone won't work while the magnetic mount is glued to the phone. If you never use the compass (most people don't), it wouldn't matter.