Hello,
UPDATE: phpdocx 10 added a caption option in addTable.
The method addImage includes the option 'caption':
http://www.phpdocx.com/api-documentation/word-content/insert-image-Word-document-with-PHP
The method addTable doesn't include it, but you can use any template to generate the DOCX replacing tables, images, caption values, adding new values...
We recommend you to read the documentation available on:
http://www.phpdocx.com/documentation
Regards.