If you are holding it in an exchange then you could tell it to them ,
But if you are holding it on your own wallet like an online wallet then contact the developer but if it is on a cold storage or an offline wallet ,
Then there is nothing that you could do .
No one can help if you your bitcoin got hacked as you cannot know who the person behind the hacked wallet address. Leaving bitcoins in exchange is the worst decision, because if exchange get hacked all your funds can get hacked and exchange will do nothing. That is why it is always recommended to store your bitcoins in desktop wallet which is more safe.