This is a big subject.
Firstly, I'm not sure it's such a great idea to spy on a child without his/her knowledge. It raises issues of trust, and can harm a relationship when the child finds out - as he/she surely will at some point.
You don't mention the age of the child but if she/he has a laptop I'm assuming it's possible to have a talk about what is and what isn't appropriate in the form of online activities. It's possible to enable parental controls on the machine of course, but the average child very rapidly finds out how to circumvent those.
What you need to understand is that sooner or later your child is almost certainly going to view what you will consider is unacceptable content - curiosity about such things is a natural part of growing up, and although as a caring parent you want to prevent your child from being exposed to the darker side of human nature you will not be able to do so for ever. It's probably far better to talk such things through, and hope that your child trusts you enough to trust your judgement in such matters.
Spying on a child's private life is the thin edge of a very big wedge.