TCPDump is far from the only tool out there used for packet capture. One of the most common tools used is Wireshark, a GUI-based tool that allows for a much deeper analysis of pcap files, in addition to capturing packets. There’s also a terminal-based version of Wireshark known as TShark.
In addition to ‘general-purpose’ packet capture software, there are also more specialized pieces of software floating around. For example, BURP Suite is a piece of proxy software that is incredibly useful for some types of pen-testing because it allows you to intercept and modify outgoing packets from your machine in semi-realtime.
Overall, packet sniffing is incredibly useful, whether you’re looking for vulnerabilities in a website or trying to jailbreak a smart treadmill. It should have a place in any hacker’s toolbox.