It's difficult to help you with an attention getter without knowing the specific topic of your essay--what aspect of "The Crucible" are you writing about?
You can always start your essay with a quote--either from the play or from another source. Just make sure you explain where the quote is from and connect it to your topic. If you use a quote, the second sentence of your introduction may be to explain the quote or explain how to relates to your topic.
You may look up what some critics have had to say about "The Crucible" and show how that relates to your topic. Make sure you show where you got the quote.
Another good attention getter is a story, also called an anecdote. It can be funny, serious, true or made up, but should somehow relate to your topic--present the problem you're going to attempt to solve, or the problem you're going to take a stance on.
Another one I've seen work well is taking a well known saying ("Absence makes the heart grow fonder" or "Don't count your chickens before they hatch") and show how your topic either supports or opposes the adage. Similar to using a quote...
Other attention getters include a startling/shocking fact or statement ("There is no such thing as truth"), a definition of a central concept ("truth", "justice") or a statistic. I don't know how well these would work for your essay.