I cannot control the sensor on my Mac, it moves by itself, and opens different pages. What can cause this problem? please help me.

Shut down the computer. Clean the trackpad with a dry microfiber cloth.

Try the tips suggested in this article from Apple.

http://support.apple.com/kb/TS1449

If this does not help, you have to take the computer to the Apple store to have it checked out.

They may be able to clean, tighten the trackpad if loose and check the battery.

Best.

By "sensor," I'm assuming you are referring to the trackpad. If so, see:

My mouse keeps moving around on its own, as if someone is remotely controlling my Mac!

If that's not what you mean, you'll need to be more specific.

There are several possible causes for this issue. Take each of the following steps until it's resolved.

1. Follow the instructions in this support article.

2. Reset the System Management Controller.

3. If you're using a Bluetooth trackpad, investigate potential sources of interference, including USB 3 devices.

4. A swollen battery in a MacBook Pro or Air can impinge on the trackpad from below and cause erratic behavior. If you have trouble clicking the trackpad, this is likely the reason. The battery must be replaced.

5. There's a report that a (possibly defective) Thunderbolt Ethernet adapter can cause the built in trackpad of a MacBook to behave erratically. If you're using such an adapter, disconnect it and test.

6. There's also a report of erratic cursor movements caused by an external display that was connected but not turned on.

7. If none of the above applies, or if you have good reason to think your computer is being controlled remotely, remove it from the network by turning off Wi-Fi, disconnecting from a Bluetooth network link, and unplugging the Ethernet cable or USB modem, whichever is applicable. If the cursor movements stop immediately, you should suspect an intrusion.