Recall that the higher the escape velocity of an object is, the more difficult it is to leave the surface of the object. That is why, less fuel was required to escape for Neil Armstrong and Buzz Aldrin to escape the Moon than to escape the Earth. (Also, the fact that the Moon doesn't have an atmosphere helped.)
Imagine you are an evil scientist. You want to build something that has such a high escape velocity that nothing can escape it. What would you do?
This is impossible because we have to increase the mass to infinity and decrease the size to zero.
Gravity isn't enough to pull every object. You will need to add magnets and electricity.
Bombard the object that needs to escape with missiles, so that it breaks up into pieces. It can then escape more easily.
Find out what the fastest-moving object it. Build something whose escape velocity is more than this object's speed.