JavaScriptでvalueで取得したサンプル

<input id="t" type="time" value="00:00:00" step="1">
<p id="r"></p>

const t = document.getElementById('t')
const r = document.getElementById('r')
t.addEventListener('input', () => {
  let [h, m, s] = (t.value).split(':')
  // if (s === undefined) s = '00'
  r.textContent = `${h}時${m}分${s}秒`
})