I just installed Prey. Ignoring the OP's use of the word "Hacker", you don't have to pay them anything to get good value from the software.

I set it up so if this file ever disappears http://iamnotaprogrammer.com/prey.html it starts sending me alert messages like the one below:

Good news my friend, it seems we found it.

Here's the report from your computer:

######################################################## # geo ########################################################

:: lat=(deleted)

:: lng=(deleted)

:: accuracy=33.0

######################################################## # network ########################################################

:: public ip=(deleted)

:: internal ip=192.168.8.121

:: gateway ip=192.168.8.1

:: mac address=34:15:9e:07:af:86

######################################################## # session ########################################################

:: logged user=sudonim

:: uptime=14:21 up 3:12, 6 users, load averages: 2.12 1.91 2.06

Happy hunting!

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Then it attaches a picture taken with my camera and a screenshot. All in all, pretty handy to have running.