Even with ADHD I've found that if you can push past the initial fidgetyness you can get a lot of good value from meditation.
If it's really out of the question for you, try yoga. It's basically just meditation + stretching and gives you something to focus your body on in the meantime. There's a lot of good YouTube videos and creators out there to do it for free on your own time and at your own pace.
It worked for me better than meditation, but everyone is different. If you do go for it, just make sure that the videos are explicitly marked as for beginners because they can end up trying some intense or weird poses you're not ready for otherwise. Personally I liked 'Yoga with Kassandra' when I was learning, but everyone's body is different so shop around a bit of she doesn't vibe with you.
If you're not used to Yoga lingo: