Packet Capture outside of ESXi

Good morning All,

I have an ESXi 6.5 installation on a bare metal server.

Within that ESXi host are four ubuntu VM's. They have been configured via scripting to make repeated FTP connections to each other and send/receive various files.

The configuration is being used for a CTF event which I am hosting.

Within the VM environment, I have no problem capturing the pcap data of the files and FTP connections being made.

The Server is being plugged in to a single switch wich my players will plug their own computers into.

When I plug into the switch, I am not able to capture the VM packet data since it's never exiting the server via a physical port.

Is there a way to configure a spanning port, or force that packet data out a physical interface?

I don't have vsphere (only ESXi) on this deployment so distributed vSwitches don't seem to be possible.

Yes, promiscuous mode is on for all of my network and virtual network devices.

I currently have a handful of Kali VM's installed on the hardware which my users could RDP into for pcap purposes, but I think that defeats the prupose of using a personal computer.

Any insight would be appreciated.