You can use the Performance Monitor counters to reveal the contents of the IIS Object Cache. The Internet Information Services Global: Objects counter counts all objects. The Internet Information Services Global: Cached File Handles and Internet Information Services Global: Directory Listings counters are subsets of the Internet Information Services Global: Objects counter. At any given time, the difference between the total number of objects and the sum of Internet Information Services Global: Cached File Handles and Internet Information Services Global: Directory Listings is equal to the number of other objects stored in the cache. Internet Information Services Global: Directory Listings are most important to servers running FTP service.
When interpreting the counters, remember that they show the most recently observed value, not an average.
The primary reason to count cache contents is to relate the contents to the size of the cache.