Droopy eyelid

Drooping Single Eyebrow
You need to see a plastic surgeon experienced in ophthalmic surgery. One frequent reason that one eyebrow is higher than the other is that you have unilateral or asymmetric ptosis (droop) of an or both eyelids. If this is the cause, you need surgical correction. If not, he/she can give you the options that are right for you.

This is a tricky question; eyelid and brow position work together and in experienced hands, you can lift the brow position in some cases with botox & fillers but it has its limitations; you should seek a consultation with a plastic surgeon that is proficient with surgical and non-surgical techniques (botox, fillers, ulthera) and discuss which option is best for you.