Whats that Source DB, if that is Hub repository then yes you can with Subscription.
If it's any source then you need to have some mechanism so that IICS objects can trigger.
more detail info can help you to fetch suitable suggestions.
My source is sql DB. And my task or mapping should be triggered once data get loaded into source table on daily basis. we have inserted or updated date column to identify the daily loaded data.
We can schedule the job using schedule option but requirement is task should be executed only after data get inserted.