Server expression equivalent for is_modified or server experession based on audit history table

Hi Experts!!!!

1. I would like to know the equivalent of is_modified function in client expression.

In client expression we have functionality is_modified in order to use similar funcationality in server expression, please let me know the options/solutions.

2. Did anyone written server expression based on aduit table or audit history, if so can you please share the server expression which you have used.

We have requirement to update series value based on audit history or audit table.

Your inputs will be of great help.

Thanks

MJ