Is it forbidden to photocopy cleaning staff timesheets and put money in exchange for that into the office safe?

The employee is entrusted with the work equipment, so it is not permissible for him to dispose of it except as explicitly or customarily authorized. Otherwise, he would be considered a betrayer of the trust. It is not permissible to photocopy documents for non-work purposes, and paying money for this does not make the act permissible, because it is an infringement on the rights of others.