Re: seems I have a problem..
I like PP's suggestion to start talking to your DS about staying safe. Obviously, you will do things like put meds and chemicals out of reach, but it's important to start teaching him that some things are only for mama or daddy to use. I also like the suggestion to put a bell on anything that might move to alert you to his position. Baby gates can help you limit his ability to move throughout the house.
With regard to teaching him to stay in his bed, it takes consistency. Every.single.time he gets out of bed, you have to put him back, and remind him that "it's time for sleeping now, stay in your bed." It will not happen overnight, but it will happen eventually. Even if he isn't ready to sleep, he can learn to stay in his bed and play with his toys, read books, listen to music, etc.
Personally, I don't like putting locks high up on the door, because I worry about getting out quickly in the event of an emergency. If that works for you, go for it. I have a friend who has had to do that to keep her SN child safe. She also has chimes installed on exterior doors to alert her to anyone opening the door (her son is a runner).