Can you get pregnant if you get fingered with some sperm on his finger?

Not sure: There is no way to be sure to get pregnant from being from getting fingered with sperm contaminated fingers. If menses are late, a pregnancy test is advised.

Unlikely: It is unlikely though not impossible, depending on the amount of sperm in the finger and your state of fertility. If it happened in the last 72 hours, if would be useful to take morning-after pill. If you miss your period by 4-5 days, do a home pregnancy test. If the result is negative repeat the test 4-5 days later unless you get a period by then. Use first morning urine and follow the instructions for the test carefully. If you do not wish to be pregnant, use contraception all the time, every time. You may consider implanted contraceptive, or IUD. Practice safe sex. Get HPV vaccine.