correct device purchase

[ulfgar]

Maybe I expressed myself badly. I have 1 magnetic window sensor 433 I acquire the signal from KCS. With mqtt I would like to create a binary sensor to see when the window is open or closed. Where can I see the code acquired from kcs to be able to create the binary sensor in mqtt?
example:
patform:mqtt
name: "window sensor"
state topic: what do I insert?
playload_on: Receiver detected code in kcs
playload_off: Receiver detected code in kcs