These stories are virtually always hoaxes.
Via Daily Wire:
In late June, Texas A&M University student Isaih Martin made headlines after he said he found racist notes on the windshield of his car.
Martin posted a picture of the notes to his Twitter page, which according to KBTX was shared more than 10,000 times. The notes said “All lives matter,” “You don’t belong here,” and one containing the n-word, Martin claimed.
“All three signs were different signs, and one said ‘All lives matter’ and the other said ‘You don’t belong here’, and the other was very explicit, it said the n-word with a hard ‘r’,” Martin told KBTX. “For them to tell me I don’t belong here, when I have earned my spot like everybody else here, and am working to get a degree like everyone else is, that was just kind of hurtful because if anything I deserve to be here just as much as anybody else.”