Install on Ubuntu
See Installing Lazarus on Linux - this page covers most of what you need for most Linux Distributions.
The easiest way to install lazarus and corresponding versions of FPC is by means of the Ubuntu Software Center that will install the lazararus/fpc version that is supported by the Ubuntu version.
apt-get install lazarus
On Ubuntu 15.10 Lazarus 1.4.0 / FPC 2.6.4 will be installed.
On Ubuntu FPC 3.0.4 will be installed in /usr/bin while Lazarus 2.0.6 will be installed in ~/.lazarus
Install a specific lazarus version from .deb:
sudo apt install gdebi sudo gdebi lazarus-project_2.0.12-0_amd64.deb