Using list of commands.
DOWNLOAD METASPLOIT

https://github.com/efxtv/metaEFX.sh.git

OR MENUAL INSTALATION
NOTE: RUN ALL THESSE COMMAND AS ROOT

sudo su
$ sudo apt-get update -y
$ sudo apt-get upgrade -y
$ apt-get update -y
$ apt-get upgrade -y
$ apt install ruby -y
$ apt install wget -y
$ apt install curl -y
$ apt install git -y

Some more requirements

$ sudo apt-get install -y curl gpgv2 autoconf bison build-essential git-corelibapr1 postgresql libaprutil1 libcurl4openssl-dev libgmp3-dev libpcap-dev openssl libpq-dev libreadline6-dev libsqlite3-dev libssl-dev locate libsvn1 libtool libxml2 libxml2-dev libxslt-dev wget libyaml-dev ncurses-dev  postgresql-contrib xsel zlib1g zlib1g-dev

Install the Metasploit

$ curl https://raw.githubusercontent.com/rapid7/metasploit-omnibus/master/config/templates/metasploit-framework-wrappers/msfupdate.erb > msfinstall

Change permission

$ chmod chmod 755 msfinstall

Start Installing the metasploit

$ ./msfinstall -y

Update metasploit

$ apt install metasploit-framework

You should also check:

Thinsg you should do after installing metasploit

How to configure Metasploit database

Search and use Metasploit Exploits