Custom Field with multiple doctype

I have created custom filed tech-stack with a selection box for project task doctype. While creating task user has to select a value from this tech-stack Combobox

Now I want to use same tech-stack custom filed in Activity Doctype and Timesheet Doc type so I can have same field value for all project-related activities.

Can anyone help here, how to use the same custom filed in multiple doctype?

You cannot use the same field for multiple doctypes. Create a new field for each doctype you want separately with the same values.

Thanks Abhijit for your clarification.