Recently I updated OpenSSH due to a PCI scan failure. We had OpenSSH 6.6 running on an Ubuntu 14.4.3 server. As of this writing OpenSSH is at 7.0 but has not been packaged for Ubuntu Aptitude yet.
UPDATE 08/23/2016: I just ran through this process again to install OpenSSH 7.3p on an Ubuntu 14.04 LTS box. Same commands worked without issue. One thing I did do different this time was uninstall the OpenSSH included with Ubuntu by running apt-get remove openssh-server. This guaranteed there was no conflict when installing from source.
This means I need to do a manual install of OpenSSH portable. It was pretty simple for me since I could use the default configuration. Your mileage may vary.
$ apt-get remove openssh-server
$ wget http://.../OpenSSH/portable/openssh-7.0p1.tar.gz
$ tar -zxvf openssh-7.3p1.tar.gz
$ cd openssh-7.3p1
$ make install
To test this you can try connecting to local host to see the ssh version returned.
$ ssh -v localhost