For ex, if it's a soap service, you will invoking a connector from Data page or tracer. Trace that particular rule and in tracer settings check Soap messages in tracer events. You will be able to see Soap request and response in tracer.
You can trace the service in your application.
Even if you are hitting the service from external system like Postman, you can see the details in service.
Please check your tracer settings. Enable the required configurations(like soap messages) in tracer.