Some of my favorite fidgets for kids are ones that are quiet, because then teachers like and allow them. All of these can be found at Office Playground website or on Amazon.
I keep a basket of fidgets in my office for kids to play with so their hands can busy. Young kids and teens body’s are not meant to stay still and need to move about every twenty minutes.
http://www.officeplayground.com/
If you or your child have a sensitive head I recommend two hair brushes the first my favorite, it hard to find it is by Aquage and called a Paddle Smooth Brush the second is the Wet Brush and very popular and easy to find. Both my children found these brushes easy to use and tolerate.