If you want to get it to stick to a vehicle or soldier (that's what you're asking right?) You'll need a loop in there. Something like:
_bomb= "timebomb" camcreate [getpos vehicle select 0, getpos vehicle select 1, (getpos vehicle select 2) + 2]
#Loop
_bomb SetPos [getpos vehicle select 0, getpos vehicle select 1, (getpos vehicle select 2) + 2]
~0.1
goto "Loop"