How to include Request Body in JWT signature

Question

How do I add request Json body in JWT Signature? JWT authorization header is only used for security purpose which means basically claims are security related information or requester details. how can I include post request body in JWT signature ?

https://localhost/Booking/Submit
JWT
.header {.alg="RS256"}
.payload { sender="ABC", recipient="XYZ", timestamp="010102020101010"}
.Signature {...}

Request Json body
{ "BookingId"=1, "BookingDate"="0404202001010", "BookedByName"="Mr. John", "BookedByContact"="12345678", "FacilitiyId"="10021"}