I have picked up more experience with carpenter bees than I desired. After I built a playset a few years ago the carpenter bees have tried to take up residence each summer since.
The biggest thing to remember, which can be hard to do at times, is that the males do NOT have a stinger and those are typically what you see flying around in the area of the nest. Typically there is a female digging the hole and the males will patrol the area. Since the males do not have a stinger there is no reason to be fearful of them - swat them with whatever you have handy - an old tennis racket works well.
For the females, you need to be more careful as they CAN and WILL sting you! For the females, I use carb/brake cleaner. I have even used a can of MAF sensor cleaner I had left over. The bees' bodies are basically held together with a waxy substance. Get a little degreaser on them and they die VERY quickly.
You can search the internet to figure out how to tell the females from the males - it's not too difficult once you understand what to look for. For every female you see there will several males around. Also, in my experience, the females are not very aggressive unless you interfere with them, whereas the males will act aggressive if you get in vicinity to try to bluff you out.
For the holes they leave behind, I typically spray a bunch of brake cleaner in the hole to kill any of the pupae in the hole then wad up some tin foil in a little ball and tuck it into the hole to ensure nothing comes in or out.
The above approach is more surgical than an insecticide bomb, but you have to find where the nest is - typically not hard to do if you watch the males for a little while as they come and go in and out of the nest. I caught a female starting a hole last week when I noticed a few males patrolling around the playset - a short blast with some brake cleaner and it died - haven't seen any carpenter bees around since!