You can track AdSense impressions and clicks in 2 ways:
- Add hubpages.com as a URL channel
- Add each article as a URL channel
I suggest the 1st way, because otherwise, you'd have to add each article manually. The only down side is that you can't see where the clicks are coming from. Another thing to mention: You can't have more than 200 custom URL channels. So if you, at any time, plan on having more than 200 hubs, adding each hub as a URL channel wouldn't work very well.
You may also link your HubPages account to Google Analytics, and link your Analytics to your AdSense account. This will give you some more AdSense-related statistics to your Analytics account.