The Wii lacks a dedicated headset port, but you can still use headphones through several methods:
Some Wii Remotes have a built-in speaker and 3.5mm jack. Plug headphones directly into the remote for game audio (mono only, not stereo).
Connect headphones to your TV's audio output (3.5mm, RCA, or optical with adapter). This provides better sound quality than the Wii Remote.
Adapters exist that connect standard headphones to the Wii's AV port, often adding volume control and microphone input.
Use a compatible Bluetooth adapter plugged into the Wii for wireless audio. Requires separate purchase.
The Wii has no built‑in microphone for voice chat. For communication, use a headset connected to a computer or mobile device instead.