Aphids.
You can spray them off with the hose when you see them, they leave some brown residue, I can see some on one of the leaves in the pics.
Home centers sell natural sprays you can drench your plant at night with it.
They are the favorite food of the ladybug. Some people actually buy ladybugs for their garden, but I have found
that spraying a spray called Organicide at Home Depot works really well, on almost any pest, and it is non toxic and natural, so really that is all you will ever need with almost all of your plants. It's concentrated, so it goes a long way. I've used it for years, but do it at night, and drench the entire plant with it.
You can use it around kids and pets, totally safe.
Your hibiscus will be beautiful, I love them, I know how you feel. Mine is blooming now, with those gorgeous big flowers.

looks like a small or juvenile shield bug.