How the three witches in Macbeth cause Macbeth and Lady Macbeth to commit crimes?

Let us be very careful here. Your question seems to
suggest that there is a direct causal link between the witches and the crime of regicide
commited by Macbeth and his wife, and that the witches "caused" it to happen, as if they
had the ability to control Macbeth and his wife like robots. Their influence is far more
subtle than this, and let us remember that Banquo is given a prophecy that guarantees
his heir the throne, yet he does not seek to commit regicide and kill his
king.

Thus the art of the witches lies in their ability to
present Macbeth with a vision of a possible future that haunts him. Note how he responds
to the partial fulfilment of the prophecy in Act I scene 3 when he is given the title of
Thane of Cawdor:

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This supernatural
soliciting

Cannot be ill; cannot be good:
-

If ill, why hath it given me earnest of
success,

Commencing in a truth? I am Thane of
Cawdor:

If good, why do I yield to that
suggestion

Whose horrid image doth unfix my
hair,

And make my seated heart knock at my
ribs,

Against the use of
nature?

Macbeth himself here
recognises the ambiguity of the prophecies he has received. The subtle influence of the
witches therefore is based on the way that they do nothing more except present their
prophecies, full of half truths, and then sit back and watch how they impact the
characters. The way that Macbeth and his wife act on his prophecies to ensure their
fulfilment points towards some inner character flaw or evil that Banquo, in the way that
he does nothing in response to his prophesy, is obviously not subject
to.