make player stuck inside of an enemy ,how to make a player stuck inside of an enemy ?

Hi, I am a newbie in unity and I need help. I have a jelly enemy that I want him to jump on the player (which he does) and that the player will be stuck inside of him and only be released if he will press the attack button fast. my primary problem is to make the player stuck inside of him. someone can help? its 2d by the way,