diff --git a/.github/workflows/commitlint.yml b/.github/workflows/commitlint.yml
new file mode 100644
index 00000000..daf956c1
--- /dev/null
+++ b/.github/workflows/commitlint.yml
@@ -0,0 +1,9 @@
+name: Lint Commit Messages
+on: [push, pull_request]
+
+jobs:
+  commitlint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: wagoid/commitlint-github-action@v5
diff --git a/quafu/algorithms/estimator.py b/quafu/algorithms/estimator.py
index dfe7ad4b..f8c8dac1 100644
--- a/quafu/algorithms/estimator.py
+++ b/quafu/algorithms/estimator.py
@@ -53,6 +53,9 @@ def _run_real_machine(self, observables: Hamiltonian):
         """Submit to quafu service"""
         if not isinstance(self._task, Task):
             raise ValueError("task not set")
+        # TODO(zhaoyilun): replace old `submit` API in the future,
+        #   investigate the best implementation for calculating
+        #   expectation on real devices.
         obs = observables.to_legacy_quafu_pauli_list()
         _, obsexp = self._task.submit(self._circ, obs)
         return sum(obsexp)