Since these three events can be considered mutually exclusive and one doesn't depend on the other, you can just multiply the three probabilities together to get the probability of getting all three of those.
- Probability of rolling a 3: 1/6
- Probability of flipping a head: 1/2
- Probability of drawing an ace: 4/52
- Probability of all of those happening: 1/6 × 1/2 × 4/52 = 4/624 = .006
This means you have a very small probability of this happening.