[gl00mie]

Well... you can set a trigger on the SqlDictionary table insert/delete to get an alert when a new field (or table/view!) is kinda created "physically" in the database (or when a table/view/field is dropped). In a database trigger you'll have to somehow connect to an AOS, enumerate user session objects and find an information about a user session that is currently using the database session in which a trigger is running (by the session SPID or something). Then you can find a record with this user session id in the SysClientSessions table and find out the userId.
Note that this way you can't monitor changes that don't alter the database scheme, e.g. changes in a field's label or EDT.