application connections MSSQL

we need to do some documentation around which SQL databases are serving which applications for asset management and CMDB purposes. Some of which have been handed over to support with no real documentation on what databases/SQL instances serve which applications, and which servers the applications are installed upon. Would there be any clues within SQL Server on which apps the databases are connected to, and what servers those apps are hosted on? Any queries which may give some clues would be a huge help!