Is there a way to query Accounts with a SystemModified date greater than a given value?

Is there a way to query Accounts with a SystemModified date greater than a given value?

A SystemModified date can be understood as the timestamp at the moment an Account or any of its related objects (like contacts) were last modified.

We need a way to query the Accounts that have been modified or which contacts has been modified.

Does such a thing exists?

Thanks in advance.

P.S. We need this because we query the Accounts modified since our last execution and extract the Account Info and its Contacts Info to update this data in our database. The problem is that when a contact is added or updated the DateModified of the Account does not change and we are not getting these changes.