We have some of our objects and fields synced to other systems and one of the common concern we see is the changes to these objects / fields (specifically deleting them in salesforce) are impacting the sync and the target systems.

So my question is how to raise an alert (say an email or an api call or any other action) when there's a change to these objects / fields 

I have already checked this question
[Identify salesforce schema changes](https://salesforce.stackexchange.com/questions/75587/identify-salesforce-schema-changes)

I believe using Metadata api to look for the changes and doing custom implementation is one option. but its more like monitoring / polling for changes and pulling the information. 

I am looking for an option (any out of the box , app exchange, custom triggers, etc.. ) within salesforce that can identify the change and raise an alert or push it out.. 

Thanks