There are all kinds of activities for permanent residents of Cape Cod, including the Wianno Club in Osterville. While getting a membership is tricky, it's worth the effort because of the access you'll have to golf, tennis, and private beaches.
There are plenty of golf courses on Cape Cod, but for residents of Barnstable, particularly those living near Marston Mills, the Olde Barnstable Fairgrounds Golf Course provides value you won't find anywhere else on the Cape.