With the Part-Time report, you can review all employees who have worked under a certain threshold of hours within a defined period. You can also view all employees who have worked 0 hours within a period.

Navigate to HR > Part-Time Report (the report may be in a slightly different place for you depending on what instance you are using) to access the report. Select your filters on the right side of the page (time period/date range, hours threshold, project/provider, task/location, time type, etc.) and click Apply Filters. The report will show any employees who logged under the specified threshold of hours within the specified date range: 

You can use the dropdown 'Zero-Hour Employees' in your filters to have the report show you all employees who have worked 0 hours within the designated period: