Yes, cocoa butter will help your black eyes because of the easy and good absorption into the skin. The black eyes will be reduced to some degree after the use of the cocoa butter. In addition, you could also have the good rest for your eyes and eat more vegetables to moisture the eyes. You could do the warm compress to make your eyes feel comfortable.
Cocoa butter is a kind health edible oil with high fiber and fat. It contains natural antioxidants which can prevent spoilage, it can also resistant winkles, make the skin delicate, enhanced sun tanned skin effect, and hide scars, etc.
So as you can see, it can help you to hide black eyes to some extents.
But in a long run, you'd better not use it because it's full of fat. And your skin can absorb then there will be another problem for you.
You may need use olive oil to massage your eyes to promote the blood circulation.
Ok, sorry to hear that your eyes have been punched, so it is true they would affect your looks and you want to get rid of them. Actually, cocoa butter consists of a lot of nutritions which could help fight against eye wrinkles, to some extent it would help with your black eyes. But what works better is some essential oils, such as lavendar oil or lemon oil, which consists of a lot of good vitamins for your eyes. Also, try to get some warm compressors and more rest.