That's easy just do the following
Download iperf2
wget https://superb-dca2.dl.sourceforge.net/project/iperf2/iperf-2.0.9.tar.gz
After download, extract archive
tar zxvf iperf-2.0.9.tar.gz
Change into the freshly extracted folder
cd iperf-2.0.9
Then run the compile of iperf2
./configure
Now run make
make -j64
Now finish the installation by typing
make install
That's it, done
Type iperf --version