You have a couple different options to monitor your incoming and outgoing Azure IoT Hub traffic.
On Windows machines, you can use the Azure IoT Hub Device Explorer utility. Under the Data tab, select your device, click Monitor and you’ll start to see messages in the Event Hub Data
You can also use the iothub-explorer npm package.
npm install -g iothub-explorer@latest
iothub-explorer hubconnectionstring monitor-events deviceid