Starting with version 2.2.1, the Virtual Appliance now supports SNMP monitoring. For details on configuration and usage, you may follow the Umbrella deployment documentation https://docs.umbrella.com/deployment-umbrella/docs/appendix-c-enable-snmp-monitoring.
The Umbrella Virtual Appliance version 2.2 and earlier does not provide SNMP for monitoring; however in most cases SNMP monitoring is available for the ESXi host itself and it might be used to monitor hardware resources. The same is also true for Hyper-V, although the setup depends heavily on your version of Windows and Hyper-V.
For more information about SNMP monitoring on VMWare, please check http://pubs.vmware.com/vsphere-50/index.jsp?topic=%2Fcom.vmware.vsphere.monitoring.doc_50%2FGUID-8EF36D7D-59B6-4C74-B1AA-4A9D18AB6250.html or inquiry with VMWare.