check if cubes are used or not

We have old SQL 2008 server which only has SSAS installed.I can login and see the cubes data sources are connecting one of our production servers.But developers in their group does not know who is using this SAAS server, or cubes?And they said no one using that as a report source either.How can I find out if there are active connections and who are using these cubes or not?Thanks