There are many ways you can protect your computer from unwarranted access. For instance, you can use Lockscreen Pro to lock your Windows 8 computer and then have the program snap a photo of the culprit using your webcam.
But if you want an even simpler and possibly more effective way to catch would-be snoopers, you should check out Mouselock. All you need is a valid Gmail address and you are good to go.
The online application is fairly simple. The app requires you to select a secret point (one of ten buttons) that will act as the pin to your computer.
Once you select the number you be asked to confirm and place the cursor inside a small gray area. Mouselock will ask to have access to your webcam if you have one. Accept if you want the program to snap a photo when the mouse is moved without unlocking.
Now you can leave your computer. If anyone moves the mouse outside of that gray circle, they have five seconds to select the secret number you applied. If they do not guess correctly, a picture will be taken and an email is immediately sent to your Gmail account.
Mouselock does not prevent people from using the computer once they have missed the secret pin. The app only informs you of the time and date of access and provides you with photographic evidence. You can also change the secret pin every time you use the app. Since there are only 10 options, it's wise to use a different number each time.
Obviously this isn't a good replacement for a strong password if you really don't want anyone using your computer. But, if you're just looking for a quick and easy way to find out who's been draining your battery while you're at work, Mouselock is a great option.