DO NOT use an ordinary vacuum or shop vacuum. The vacuum will put mercury vapor into the air and increase the likelihood of human exposure. Several types of non-mercury thermometers are available commercially. Digital electronic fever thermometers are readily available at retailers. There are also digital basal thermometers for family planning that can be used instead of mercury basal thermometers.
Alcohol thermometers are currently less easy to find at retailers.
Galinstan thermometers have recently been approved by the Food and Drug Administration. What's most important is that you choose a thermometer that's easy to use and read. The newest thermometers available are ear thermometers that quickly and easily measure temperature inside the ear canal. They are still fairly expensive compared with glass and electronic models, and learning how to use them correctly takes some training. But they can be quick and relatively comfortable for children.