Anything can be captioned. Also captions are not real, correct captions but just a paragraph below the element (bothe wrapped into a div)

#+CAPTION: captioned soure block
#+BEGIN_SRC sh
echo "i have a caption!"
#+END_SRC

#+CAPTION: captioned link (image in this case)
[[https://placekitten.com/200/200#.png]]

note that the whole paragraph is captioned, so a linebreak is needed for images to caption correctly

#+CAPTION: captioned link (image in this case)
[[https://placekitten.com/200/200#.png]]
see?