Some disease-causing organisms, or pathogens, can thrive and multiply for some time on an object like a phone receiver spattered by the saliva of an infected person.
But most bacteria and viruses quickly die when moisture disappears, usually after one or two hours for the saliva spray.
Different pathogens have different survival times, ranging from a few minutes or hours to days or even months, and some might lurk for weeks or months on an object like a door handle in the house of someone with hepatitis A.
In such cases, infectious disease specialists recommend frequent hand washing and avoiding touching your eyes or mouth; such measures would cut your infection risk to a very low level.
Using the damp toothbrush of someone with some infectious diseases would be a very likely way to get sick yourself, but cold viruses are usually spread by hand-toeye or hand-to-mouth contact.