Lets start small! In this topic I will share how you can know your ESXi version on the cluster. 

I understand that you want a quick way to verify ESX version on Prism, in Prism, although we do show the Hypervisor the cluster is running on, but currently the Prism UI does not show the hypervisor version.

Perhaps a command may fit better your purpose. For this you can issue the following command from any CVM.

nutanix@cvm $ hostssh "esxcli system version get"

The above, will query each node to find out the version of ESXi it is running.

Alternatively you could also use commands like-

nutanix@cvm $ hostssh vmware -v (command specific to ESXi hypervisor)

nutanix@cvm $ hostssh uname -a (hypervisor agnostic command)