The VM here is irrelevant as it doesn't provide any useful information.
The case fans of an ESXi host which HW is Supermicro, I don't know if it has but, this did you check the iLO?
Or do you mean to monitor the fans from a VM within the host? It really doesn't make sense...
But basically, you need any tool to gain access to the host (usually servers have a remote management web page where you can see the HW) or to configure SNMP traps to send them to any monitoring tool.