Simply load your home page into a browser and select “view source.”  Most browsers can  display the web page source. Usually, on a PC, it can be found as an option after pressing right mouse button.  Once displayed simple use the search option (cntrl + f) and look for the following “meta name=”generator”

The line will look something like this for version 4.4.1

<meta name="generator" content="WordPress 4.4.1" />