You can create a Table of Design Points simply by clicking the empty box next to the Z Coordinate to create an input parameter.

In Workbench, there will be a Parameter Set box, click on that to see the Table of Design Points.

Type as many rows for the Z Coordinate that you want solved.  At the end of the row, check the Retain Design Point if you want to look at each solution.

If you don't need to see the complete solution for each row, but a few numerical outputs, in Mechanical, click on one of your results such as Maximum Principal Stress and in the Details window, in the Results category, you will see a row for the Maximum Value with an empty box. Click on that to create an output parameter. In Workbench, on the Parameter Set Table of Design Points, you will see a column created to hold that output.

You can automatically run all those solutions from Workbench by clicking on the Update All Design Points button.