Read wordpress post headline as summary

Hi,
I have 2 sites, A site and B site, but only B site is build with wordpress.

I want to read headlines from B site (wordpress) post content, I guess I have to develop a plugin for it to read it from B site.
for example, I do a post on B site, in the content, I added h1, h2, I want to read those h1,h2 as summary and put on A site.

I am wondering is there any ready to use plugin available?

Thanks