As first you need elementary SDK
sudo apt install elementary-sdk
Install dependencies
sudo apt install libgstreamer1.0-dev
Clone repository and change directory
git clone https://github.com/artemanufrij/metronome.git
cd metronome
Compile, install and start Metronome on your system
meson build --prefix=/usr
cd build
sudo ninja install
com.github.artemanufrij.metronome