1. Baixe o Microsofy ODBC DRIVER 17 PARA SQL SERVER

https://docs.microsoft.com/pt-br/sql/connect/odbc/linux-mac/installing-the-microsoft-odbc-driver-for-sql-server?view=sql-server-2017

Ubuntu 14.04, 16.04, 17.10 e 18.04

Copiar

sudo su 
curl https://packages.microsoft.com/keys/microsoft.asc | apt-key add -

#Download appropriate package for the OS version
#Choose only ONE of the following, corresponding to your OS version

#Ubuntu 14.04
curl https://packages.microsoft.com/config/ubuntu/14.04/prod.list > /etc/apt/sources.list.d/mssql-release.list

#Ubuntu 16.04
curl https://packages.microsoft.com/config/ubuntu/16.04/prod.list > /etc/apt/sources.list.d/mssql-release.list

#Ubuntu 18.04
curl https://packages.microsoft.com/config/ubuntu/18.04/prod.list > /etc/apt/sources.list.d/mssql-release.list

#Ubuntu 18.10
curl https://packages.microsoft.com/config/ubuntu/18.10/prod.list > /etc/apt/sources.list.d/mssql-release.list

exit
sudo apt-get update
sudo ACCEPT_EULA=Y apt-get install msodbcsql17
# optional: for bcp and sqlcmd
sudo ACCEPT_EULA=Y apt-get install mssql-tools
echo 'export PATH="$PATH:/opt/mssql-tools/bin"' >> ~/.bash_profile
echo 'export PATH="$PATH:/opt/mssql-tools/bin"' >> ~/.bashrc
source ~/.bashrc
# optional: for unixODBC development headers
sudo apt-get install unixodbc-dev

Instalando via pip o pyodbc

pip install pyodbc

Exemplo

import pyodbc
# Some other example server values are
# server = 'localhost\sqlexpress' # for a named instance
# server = 'myserver,port' # to specify an alternate port
server = 'server_dns,2127'
database = 'banco'
username = 'nome_do_usuario'
password = 'senha_do_usuario'
cnxn = pyodbc.connect('DRIVER={ODBC Driver 17 for SQL Server};SERVER='+server+';DATABASE='+database+';UID='+username+';PWD='+ password)
cursor = cnxn.cursor()

cursor.execute("SELECT top 10* FROM tabela")
tables = cursor.fetchall()
for row in tables:
    print(row)