Can I control laptop's camera using Arduino sketch or IDE without connecting a separate Arduino Board?
No. The Arduino IDE is to program microcontrollers. You can't use it to program your computer. There are many other applications you can use to do that.
Please provide a detailed description of what you're trying to accomplish.
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What ever you could write to an Arduino you could code in C on your own computer / laptop.
The language called Processing is free and runs on all platforms. While it is Java like, Java has a C syntax so it is easy to write if you know C already.