hi there,i have a question, please help me !

We don't have anything out-of-the-box yet for head bobbing, but it's on our to-do list.

In the meantime, the best way to do it would be with a custom CinemachineExtension. Have your custom extension add the bob motion to the vcam's PositionCorrection field of its state (it's a position delta, so a simple sinusoidal motion about 0 on the Y axis should do the trick). This way it will coexist with Perlin noise and other stuff, and will blend.

See this post for a sample CinemachineExtension: https://forum.unity.com/threads/how-to-shake-camera-with-cinemachine.485724/#post-3416266
The code there randomly shakes the camera, but you can use it as a jumping-off point for your head-bobbing feature.

Good luck! If you come up with something cool, don't hesitate to share it here

PS you can copy the Perlin Noise presets and customize them, or make your own using the Noise Settings editor. It can be used to generate all sorts of signals, including non-random sinusoidal ones. Click on that little gear icon for options: