To use precompiled wheels:
1) go to releases (Files) and download tarball needed;
2) install it with command:
python3 -m pip install /path/to/wheel.whl
Or simply use URL in pip:
python3 -m pip install https://sourceforge.net/projects/gdal-wheels-for-linux/files/GDAL-3.1.4-cp37-cp37m-manylinux_2_5_x86_64.manylinux1_x86_64.whl/download
URL may be found under "View details" button (i)
To use GDAL in C/C++ project you need to link gdal lib AND all libs located at dir GDAL.libs...