You can read the innerHTML attribute to get the source of the content of the element or outerHTML for the source with the current element.
Python:
element.get_attribute('innerHTML')
Java:
elem.getAttribute("innerHTML");
C#:
element.GetAttribute("innerHTML");
Ruby:
element.attribute("innerHTML")
JavaScript:
element.getAttribute('innerHTML');
PHP:
$element->getAttribute('innerHTML');
It was tested and worked with the ChromeDriver.