"child of" constraint

thanks for the hint. but i just found out this video. which's solved my problem https://www.youtube.com/watch?v=7hq92JvHq2g

ooooooor you can use shrinkwrap

ooooooor u can use hook

Shrinkwrap doesn't work well on objects with depth. (like the one in the thumbnail) And if you mean sculpt mode hook, then that would take longer and have a worse result.

that's why you use lattice