I often see an active process in Activity Monitor in SSMS, its detail likes the following.
create table #tmpDBCCinputbuffer ([Event Type] nvarchar(512), [Parameters] int, [Event Info] nvarchar(512))
insert into #tmpDBCCinputbuffer exec ('DBCC INPUTBUFFER(72)')
select [Event Info] from #tmpDBCCinputbuffer
It is the process of Activity Monitor itself.