Select the VM (or search for it), click "Troubleshooting" and then "all metrics". Select the CPU parameter you need and adjust time.
You could also do it as a "View" or via API calls.
A quick guide to using "Views" look here: Troubleshooting with vRops part 3: Object Level Metric - Michael Ryom
If you do create a "view", all you need to do is set the time period, change "transformation", and select the right metric.
The API(The hard) way take a look at this: vRops API consumed with Powershell - Michael Ryom
Hope this helps
