The earlier replies are correct and you'll need to look at this info either at an individual port level in somewhat real time, or aggregated in a summary report. That info is not syslogged or event logged for example. And unfortunately there is no API call today that will return the instantaneous PoE power draw on a port by port basis either. There are however errors for PoE overload and warnings for PoE power being denied.
Curious, since it would be a ton of data, what is the use case for needing to track instantaneous PoE usage port by port? Or perhaps it's more about alerting? Perhaps the feature request would be to add an alert on the Network-Wide > Alerts page to have an alert if a port is denied PoE power, so you could start being alerted if a switch is over budget and some devices cannot get power.