Current version of sphinx on Ubuntu 14.04 is 2.0.*

If you need a more recent version, you can find a .deb package directly on Sphinx website : http://sphinxsearch.com/downloads/release/

Pick-up your package and install it locally :

$ wget http://sphinxsearch.com/files/sphinxsearch_2.2.6-release-0ubuntu12~trusty_amd64.deb

$ dpkg -i sphinxsearch_2.2.6-release-0ubuntu12~trusty_amd64.deb

$ searchd -h
Sphinx 2.2.6-id64-release (r4843)
Copyright (c) 2001-2014, Andrew Aksyonoff
Copyright (c) 2008-2014, Sphinx Technologies Inc (http://sphinxsearch.com)
...