Yes, you can definitely use a trimmer for your pubic hair as long as the trimmer is made from high-quality material and it's waterproof.   However, keep in mind that it's easy to slip and hurt yourself with a trimmer, so you should stay very vigilant.   If you're uncomfortable trimming your private parts with a machine, then you can do it manually using scissors instead. Besides that, there shouldn't be any problems with using a trimmer.