There is a strange sound coming from underneath the hood of the car. It sounds like static electricity.

Nothing major has happened to the car. Today, I was pulling up to an ATM and I heard this noise that I thought was coming from the machine but when I pulled away, the noise followed. I went to a fast food place and while waiting in the drive thru, I noticed the sound was getting a little louder. I pulled up my driveway and the traction engaged message came on and there was a difference in the steering, of course, and I did not turn the engine off but sat there to hear the noise and it eventually quit! Any ideas please? This grandmother hopes it's not bad news.