Have you ever had the need to retrieve the previous value in the same manner that you do when using the previous object in a Business rule?

There is actually a way to accomplish this.

Since ServiceNow stores most changes in the sys_audit table you can go there to get all previous values if needed.

A fair warning though, the sys_audit table is huge, so don't go down this path if not absolutely necessary.

Now to the solution;Create a Subflow that takes input parameters on which table, field name, record sysid, and created by.

The subflow itself will be simple, it does a look up on the audit table, using supplied input parameters to get the result, and returns the "oldvalue" value.