You can check here for getting the latest version. Change the wget url to download newer versions.
$ wget https://github.com/wkhtmltopdf/wkhtmltopdf/releases/download/0.12.4/wkhtmltox-0.12.4_linux-generic-amd64.tar.xz
$ tar -xvf wkhtmltox-0.12.4_linux-generic-amd64.tar.xz
$ cd wkhtmltox/bin/
$ sudo mv wkhtmltopdf /usr/bin/wkhtmltopdf
$ sudo mv wkhtmltoimage /usr/bin/wkhtmltoimage
$ sudo chmod a+x /usr/bin/wkhtmltopdf
$ sudo chmod a+x /usr/bin/wkhtmltoimage
$ wkhtmltopdf http://www.google.com google.pdf
If showing something like this...
Loading pages (1/6)
Counting pages (2/6)
Resolving links (4/6)
Loading headers and footers (5/6)
Printing pages (6/6)
Done
so works. : )