hang by something
1. to be suspended at the end of something, such as a rope, chain, string, etc. The bag is only hanging by a string. The food hung by a rope from a tree to protect it from the bears that wandered into camp now and then.
2. to dangle, suspended by some body part, such as thumbs, legs, etc. I was hanging by my legs on the exercise bar when the rain started. I can hang by just my middle fingers!