How to add custom HTML block in Form page?

Hi,
When I open Project form page it shows Activities and Connections on the top. Is it possible to add my own custom HTML block there?

Maybe it is possible, but what is the scenario to know whether it is possible or not.

What do you want to add?

I have added some new fields in Project and on basis of those fields I need to show some calculations.

Want to make something like this?

Yes! How is it possible to do that?

Reference: How to Change the Label of a Dashboard Indicator in Customer Doctype - #5 by NCP