Can fingering a girl with a small amount of pre cum can get her pregnant? What are the chances? Has there been any record of getting pregnant like this

Yes it can. The likelihood is low, but still possible. I can't give you a specific number. If you don't want to create a pregnancy, use a condom for every sexual act and don't expose the woman to pre-cum. Best wishes.
Yes. Anytime sperm enters the vagina there is a chance of pregnancy. In terms of putting an exact number to that chance, that is very difficult to say. Probably pretty low if i were making a guess i'd say less than 15%. But that is solely an estimate.
Possible. Pre-cum does contain semen and if placed in the vagina with you finger could cause pregnancy. It only takes 1 sperm to get pregnant.
Precum. Is the clear, colorless, viscous fluid that is emitted from the urethra of the human penis during sexual arousal. The presence of sperm in the fluid is debated. Research has found no or low levels of sperm in pre-ejaculate, though these existing studies are non-generalizable due to examining small numbers of men. The answer is maybe....Though unlikely.