As it’s not available in repo nor PPA you need to build it (it is really easy and quickly done).
Fetch and extract
wget -c https://github.com/raboof/nethogs/archive/v0.8.1.tar.gz
tar xf v0.8.1.tar.gz
Install dependencies and build
sudo apt-get install libncurses5-dev libpcap-dev
make && sudo make install
Check and run