I recently cancelled my satellite service and need to take down my satellite dish. I will have a hole about 2 ->2.5" in diameter. I didn't want to replace the siding, I just want to patch it. I got some caulking for siding, my question what do I fill the hole in with? Should I use just the caulking or do I need more and then use the caulking? Probably a dumb question. Please help.

I would fill the actual hole in the wall with spray foam insulation. If there is any bulge after it cure you can shave it with a knife. I don't know how much you want to try to hide the hole but you could glue a scrap of siding over the hole, color matching will be iffy.