https://github.com/WiringPi/WiringPi/releases

install method 1

Unzip/use the portable prebuilt verison:

# unzip the archive
tar -xfv wiringpi_3.0.tar.gz

Install the debian package:

# install a dpkg
sudo apt install ./wiringpi-3.0-1.deb
sudo apt install ./wiringpi_3.10_armhf.deb
sudo apt install ./wiringpi_3.10_arm64.deb ## install method 2 

wget https://project-downloads.drogon.net/wiringpi-latest.deb
sudo dpkg -i wiringpi-latest.deb

install method 3

sudo apt-get install wiringpi

ref