You can use a "network sniffer" to observe data packets on your local network which are sent from or received by your computer.

It will be helpful to study the Bitcoin network protocol documentation so that you can define a filter that will only show the Bitcoin related traffic.

A popular choice for Windows is Wireshark, but there are many other options. If Wireshark does not have a decoder (dissector) for your protocol of interest you may have to manually decode from hex.

See https://www.google.com/search?q=wireshark+bitcoin+dissector -- there seem to be several bitcoin dissectors you can add to Wireshark.