These lighters make a very high frequency noise that humans cannot hear. But your pets can. I found out by accident and decided to have some fun testing it.

As shown in the video, the dB level is not harmful. However I would not recommend you to hold this closer to your ear out of curiosity. The cat is reacting to the noise simply because she doesn't understand it. It only scaring her and is not harming the ears. If it was harmful then a persons hearing would be damaged too even though the sound in not perceptible. It's the same reason why an invisible laser light can blind you even if you can't see it. It's all about the intensity. In the case of noise though, pitch has little to do with it. Just like the wavelength (color) of a laser has little to do with causing harm.

If you are interested in the lighter, here is a link. It is an affiliate link.
https://amzn.to/3lHwqCQ