The error

While you are install gettercap and you get the error:

go/src/github.com/bettercap/bettercap/vendor/github.com/google/gopacket/pcap/pcap.go:22:18: fatal error: pcap.h: No such file or directory
 #include <pcap.h>

Solution

Try to install with apt:

sudo apt-get install libpcap-dev