Occasionally ESXi users want to check CPU microcode. You can check CPU microcode revision on running ESXi host this easy way.
[root@tanzu-esxi-1:~] vsish -e cat /hardware/cpu/cpuList/0 | grep -i -E 'family|model|stepping|microcode|revision'
Family:0x06
Model:0x25
Stepping:0x01
Number of microcode updates:0
Original Revision:0x0000001f
Current Revision:0x0000001f