To research how this might be achieved programmatically, I would recommend starting off with the standard research approach to find a Revit API solution:
https://thebuildingcoder.typepad.com/blog/2017/01/virtues-of-reproduction-research-mep-settings-onto...
Check how to achieve the desired result manually, e.g., searching for something like 'revit dimension style create a new arrowhead tick mark':
https://duckduckgo.com/?q=revit+dimension+style+create+a+new+arrowhead+tick+mark
Analyse the properties and relationships of the affected elements, and then see whether the same can be achieved programatically.
Browsing a bit further, though, I see that you might very well run into a limitation; I searched for 'revit dimension style create a custom arrowhead type' and encountered this:
https://knowledge.autodesk.com/support/revit-products/troubleshooting/caas/sfdcarticles/sfdcarticles...
Issue:
It is not possible to load a custom arrowhead when browsing to Manage > Additional Settings > Arrowheads
Solution:
Customize the existing Arrowhead System Family.
An enhancement request in order to load custom families into the Arrowhead options has been logged on Revit Ideas. To see it and vote it up, see:
Custom leader arrowhead
See Also:
So, I guess it depends a bit on exactly what you wish to achieve.