How to create sub column header in this case?

[catpoisoncat]

In Power Query

This is the original table in power query above.

What I want to get.

This is what I want it to look like in my report (the highlighted part).

I used EXCEL only to demonstrate what I wanted in Power BI report format (since I don't know I to do it in Power BI).

I've tried unpivot and transpose, but maybe my steps are wrong, I just couldn't get the output that I wanted.

Thank you for your help.

@v-yueyunzh-msft 

[amitchandak]

@catpoisoncat , In the matrix Office and Month, need to row, then you think about header grouping, using calculation group  or unpivot

column header grouping
https://www.daxpatterns.com/dynamic-segmentation/
https://community.powerbi.com/t5/Desktop/Matrix-Display-Values-above-Columns/td-p/256905
https://community.powerbi.com/t5/Desktop/grouping-measure-results/td-p/456795

Calculation Groups- Measure Slicer, Measure Header Grouping, Measure to dimension conversion. Complex Table display : https://youtu.be/qMNv67P8Go0