Network Watcher variable packet capture allows you to create packet capture sessions to track traffic to and from a virtual machine. Packet capture helps to diagnose network anomalies both reactively and proactively. Other uses include gathering network statistics, gaining information on network intrusions, to debug client-server communications and much more.
Reference:
https://docs.microsoft.com/en-us/azure/network-watcher/network-watcher-packet-capture- overview