Why do you want to specifically monitor the temperature data of the server?
Are you feeding it to a monitoring solution or NMS like OpenNMS, Zabbix, etc.? Or are you just concerned about the thermal health of the server?
The model of server matters a little, because different ProLiant systems have different temperature thresholds and thermal profiles. Please let us know what you're using.
Generically, the common approach to this is to set the proper alarm actions for your server's health in your vCenter. This assumes you're using vCenter to manage the system. If so, set your SNMP monitoring system to receive traps for "Host hardware temperature status" events, that's a good way to monitor the system. In fact, by default, vCenter sends traps on these events.
While I can see individual temperatures for the 27 sensors on my ProLiant DL360 G7, I don't actually care if it's the 3rd memory module that's overtemp or the drive backplane. I care whether the host thinks it's healthy overall or not...
Now, if I'm off-base here, and you don't have vCenter are are trying to monitor a single server, use either this guide or this guide to establish an SNMP configuration on your ESXi server.
You may also be able to pull the relevant information from your ILO's web interface, via SNMP passthrough or even SSH. Some of that is covered in: automatic get server temperature via HP iLO