The play itself
Though there isn’t a lot of symbolism in the story, the events in the play itself are an allegory for the intolerance of McCarthyism. For a decade spanning the late 1940s to the late 1950s, the American government was intensely suspicious of the possible influence of communism on citizens and institutions. The FBI accused thousands of people of “un-American activities” and monitored many more; these people’s careers and personal lives were frequently destroyed. More often than not, there was little to no evidence to support the accusations. Nevertheless, the FBI and various government groups involved in monitoring or accusing individuals, such as The House Un-American Activities Committee, enjoyed widespread support from the American population. (Learn more here.)
Similarly, in The Crucible, there is little evidence that much witchcraft activity is going on, but once accusations started flying, many innocent people get caught in the web of hysteria. Lives are destroyed and people die based on zero evidence.