<div class="foo"><input type="text"></div>
.foo {
position: relative;
box-sizing: border-box;
}
.foo input {
padding-left: 1em;
}
.foo::before {
content: '$';
position: absolute;
top: 2px; left: 3px;
pointer-events: none;
}
https://jsfiddle.net/1uhgL0mx/