why everytime I appy my brake i hear a knocking sound

Hello, I think the noise is happening as weight of the vehicle and inertia shifts, not so much a brake system problem if the noise you hear seems to be inside the door. Seek the assistance of a technician near you who can observe the noise you are speaking of and if needed, remove the door panel on the affected door to see what might be loose inside. Seek local guidance at a shop near you -- check this link to find some choices: www.repairpal.com/repair-shops