How do i track usage of a heap table ?
Heaps are tracked in sys.indexes and sys.dm_db_index_usage_stats with index_id=0.  Try

select 
   db_name(database_id) database_name,
   object_name(object_id,database_id) table_name,
   s.*
from sys.dm_db_index_usage_stats as s
where index_id = 0


You should see your heap tables.