There is definitely a lot of suspicion abound in Macbeth.
First of all, Macbeth is suspicious of Banquo and Banquo is suspicious of Macbeth. Both have heard the prophecy. Banquo wonders why Macbeth seems interested in it, and tries to warn him not to listen.
Thou hast it now: King, Cawdor, Glamis, all,
As the weird women promised, and I fear
Thou play'dst most foully for't: (Act 3, Scene 1, p. 40)
Yet Macbeth also wonders about Banquo, since he is not pleased with the “fruitless crown” since Banquo’s sons are supposed to be king, not Macbeth’s.
Macbeth is also very suspicious of Banquo after he kills Duncan. Duncan, who should have been suspicious of Macbeth, was not.
To be thus is nothing,
But to be safely thus. Our fears in Banquo
Stick deep, and in his royalty of nature
Reigns that which would be fear'd. (Act 3, Scene 1, p. 42)
Suspicion runs deep. Malcolm is also suspicious of Macduff, and tests his loyalty before allowing him to assist in taking back the crown. He tries to tempt Macduff into agreeing with him that he is unfit to rule, but Macduff passes the test.
Macduff, this noble passion,
Child of integrity, hath from my soul(130)
Wiped the black scruples, reconciled my thoughts
To thy good truth and honor. (Act 4, Scene 3, p. 70)
In the end, Macbeth begins to worry. He refuses to hear reports of desertion or soldiers coming for him. He is right to be suspicious though—they are coming!