You can construct an interactive graph with a slider to trace the plotted function. As a proof of concept, you can check the interact given in this SageMath Cell. For the sake of completeness, I copy here the corresponding code:

```
f(x) = sin(2*x)-3*cos(x)
xmin = -2*pi
xmax = 4*pi
@interact
def _(xx=slider(xmin,xmax,default=xmin,label="x"),
trace=checkbox(default=False,label="Trace")):
p = plot(f(x), (x,xmin,xmax), color="green")
if trace:
p += text(r"$({0:f},{1:f})$".format(float(xx),float(f(xx))),(xx,f(xx)),
color="black", vertical_alignment="top")
p += point((xx,f(xx)), color="red", size=30)
show(p)
```

What do you mean by "trace"ing a graph ?

Graph Trace lets you move a trace cursor over the points of a graph or plot and displays value information. On TI calculators there a button labeled TRACE, that does just that.

This is to which @gg refers, I think.