I have, over the years, used many, many coping strategies for adhd. None work for all, but we can usually find some that work for some, and approach it that way.
In today's overcrowded middle school classrooms, I have a set of headphones that they can wear; nothing to plug into, but it helps quiet the sounds around them. I have had a series of special passes that I've used for those extreme "H" kids; each time they finish a task, they can ask for a pass to take them somewhere. Generally to the playground for a few minutes. I had one boy who just wanted to run laps. He was bright and motivated. He really just wanted to run, so he quickly learned to focus long enough to finish each task, and then he'd go out and run a mile or so, coming back in flushed, with bright eyes and a grin, ready to dive into whatever came next.
These are also the kids I pick most often for running any kind of errand. To the office, to the library, to another teacher's room...I tend to make sure I've got plenty of errands on hand at the beginning of the day just for this purpose. It's a win/win. They get movement and a break, plus they are helping. It's positive.
This last year we tried fitness/stability/balance balls to replace some students' chairs, and it worked well for some of them. It gave them an excuse for squirming, and took energy and focus to stay balanced while at their seats. Of course, the rest of the room was envious, but I didn't have the budget to replace ALL the chairs.
And, of course, the easiest and most often used is simple redirection, done with eye contact and/or a soft, supportive voice. That just takes patience and vigilance on my part.