There is a second aspect that needs to be considered - the "transport medium" - if it's bluetooth, the "sniffer" will need to be bluetooth equipped, if it's WiFi, the "sniffer" will need to be WiFi equipped - OR - the network will have to be configured to route the traffic to the PC so it can be seen.
I'm not familiar with the ins & outs of bluetooth, but for tcp/ip networking using WiFi & ethernet, the network adapters, or specifically their drivers need to support promiscuous mode, and as far as I know, few WiFi adapter manufacturers make promiscuous mode drivers available, it may be easier to find a promiscuous mode driver for an ethernet card, but, most ethernet based networks are now switched networks, and the network switch used will need to support port monitoring, if not, a MITM hack will be needed - easier said than done on a typical residential network where the internet gateway acts as firewall/router/switch and wireless access point.
After all of this has been setup - you'll be able to see the traffic using WireShark or similar, and you'll need to learn how to filter out what you're interested in, and then most likely encryption will be your next problem.