Get him checked in case he is hyperactive and there are ways you can help him with that.
Bad behaviour should still not be used as an excuse but helping him be stimulated may help reduce that and any bad behaviour after that should be tackled.
As a child me and my brother were always read to lots, learnt to read and write early, learn to play music, learn things like chess and board games like trivial pursuit. I did a lot of dancing and drama as well, RAF cadets, climbing and other outdoorsy stuff. When I was younger I did brownies and guides and loved going for the different badges and doing things like orienteering and acavenger hunts.
My father especially would give us little quizzes all the time, say classical music when it was on at home, plants and birds and such such we went out on walks, we used to have general knowledge quizzes in the car, all kinds of things.
Things like atlases and maps facinated me and I loved things like lego and, when older, mechano and sciencey things
Science is quite good as you can do a lot of stuff very cheaply with household stuff and you can get kids chemistry sets and stuff for older kids.
How about things he can watch like plants growing, esp the more unsual ones (I grew a peanut plant in junior school which actually grew peanuts).
I used to be down the library all the time and loved learning other languages and skills, I was very arty and crafty as well (when other kids made cushions at school I made a fully lined waistcoat).