Thank you for writing.
Condoms are up to 98% effective and there was no ejaculation inside so the risk is even less.
As far as pre-ejaculate is concerned, pre-ejaculate itself does not contain any sperm. Sperm may be inside the urethra if a man ejaculated recently and did not urinate since. If he urinated since he last ejaculated, there is no sperm at all. Pregnancy is very uncommon from pre-ejaculate and the urethra would have to contain sperm at the same time. A woman would also have to be ovulating and engage in unprotected intercourse with ejaculation.