How to enable CDN for a subdomain with external web server


My landing page is a static built website. Then I have a subdomain, which is an A record in DNS. This subdomain is pointed to an external web server (Django API), which provides REST API and serves static content.
The question is how can I make this subdomain to use Netlify CDN, when serving static content from Django API?

I tried my best to look for such a question, but I couldn’t pick the right terms, I suppose, so I didn’t find it.
I would be very grateful for any advice!

Thank you and best regards!

I believe, this has been answered here:

Yes, I saw your answer, thank you!