MCAUballs allow players to catch passive animals to transport them to a new location.
Not every entity can be caught with a MCAUball. The general rule is it has to be a passive animal.
This means you may not catch villagers, zombies, skeletons, etc.
To capture a mob, aim for the ground near their feet. There is a small chance that the mob may break free and you will lose your MCAUball.
If you are successful, you will recive the filled MCAUball in your inventory. To release the capture mob, simply throw it at a vacant position on the ground.